The main objective with this project is to learn more about the role of genetic and environmental factors in the development of the central nervous system. The request is for a continuation of our studies of the visual system in normal and visually deprived monkeys and cats. Receptive field analysis of single cells will continue to be our main technique in these studies but other methods are certain to be used more and more to complement the physiology. The new anatomical techniques developed during the last few years have already proven their usefulness and we foresee new developments in this area. Behavioral studies will continue to be used to raise monkeys under various conditions of visual deprivation. The neurochemical work on the vertebrate retina will be continued; this approach is not yet fully integrated with our studies of the mammalian visual system but we intend to adapt the methods developed for studies of normal and visually deprived animals.